The present invention relates, in general, to an improved electrical connector system, and more particularly, to a micropin system which incorporates a two-part connector housing including a plug component, and a socket component. Each component is adapted to receive corresponding pin terminals and receptacle terminals formed on the ends of interconnect wires and is shaped to facilitate the assembly of wire harnesses. The connector system provides plug and socket terminations at the ends of such harnesses for in line connections to corresponding terminations on other harnesses or for header connections to suitable electronic components such as microprocessor control elements, sensors and the like.
The rapid development of electronic systems for a wide range of industrial products and consumer goods has resulted in a heavy demand for improvements in the wire interconnects between electronic control components, the sensor elements connected to various parts of appliances, automobiles, and the like, and the various elements being controlled by such electronic components. These wired interconnects are often in the form of wire harnesses, wherein multiple wires are secured together to provide connections between specified locations and wherein the wires are provided with plug and socket terminations for interconnection with electronic components or other wire harnesses. A typical example of these harnesses and the corresponding lug and socket terminations is found in automotive applications, where increasing numbers of electronic sensors and control systems are being provided, requiring larger quantities of wire interconnects and increasingly complex wiring harnesses to provide the required connections to the various system elements.
The expanding use of wire harnesses and the increasing number of plug and socket terminations for such harnesses has highlighted the problems that have been encountered in prior interconnection systems, for as additional connectors are used, it becomes increasingly important to provide connectors which can easily be connected and disconnected and, even more importantly, can be automatically or manually assembled in harnesses accurately and easily so as to insure reliability while maintaining as low cost as possible. Generally, wiring harnesses utilizing multiple wires connected to the plug and socket components forming the harness terminations have been hand assembled, with individual wires being inserted into corresponding connector locations on both the plug and socket ends of the harness. The assemblers must select specific cables or wires for specific connections in the harness, and must secure them accurately and reliably to the corresponding plug and socket components. The plug and socket components must be constructed so that there is a positive lock for the individual wire terminals not only to retain the wires in place during the assembly process, but to enable the assembler to know that the wire is positively seated in its respective connector components. At the same time, the wires must be removable from the plug or the socket in case an error is made, so as to avoid the need to discard an entire harness if one wire is put in the wrong location. This requires a careful design of both the terminal on the end of the wire and the receiver in the plug or socket portion of the connector so that the wires can be easily handled without tangling and so that the terminals can be inserted into the connectors easily and accurately, while being removable in case errors are made, so as to insure proper positioning for reliable interconnection with electrical components or other wiring harnesses.
One solution to the foregoing problems found in the prior art was a locking wedge system, wherein a connector housing was provided with a plurality of flexible locking fingers which engaged detents or indentations formed in wire terminals positioned in the connector to secure the wire in place. The indentation on the terminal allowed the finger to engage and secure the wire while the flexibility of the finger permitted the wire to be removed without undue force. After assembly of the wires in the harness to the connector, a wedge was placed between adjacent fingers in the connector to prevent the fingers from flexing and to thereby securely lock them in contact with the wire terminals. This also assured the assembler that the terminals were fully in place, for if any one terminal was not fully inserted, the corresponding finger would be held out of position, and this would prevent the wedge from being inserted.
The locking wedges provided a satisfactory solution to the above-described problems as long as the overall size of the connectors was not a consideration. However, when the growth of electronic systems further increased the number of wires to be included in a harness, and the miniaturization of electronic components placed restrictions on the size of the connectors for these harnesses, problems arose with the locking wedge style of connector. The miniaturization of the harness terminations initially involved simple downsizing of the connectors, but it was soon found that the locking fingers became very fragile as they were made smaller, and the strength and reliability of the connectors suffered. Further, the fragility of the locking fingers made them susceptible to damage upon insertion of a locking wedge if one of the wires was not fully inserted in the connector.
As more wires were included in a harness and as the connectors were made smaller, the wires were forced into close proximity, not only making the assembly of a harness more difficult, but also causing significant problems in the manufacture of the connector itself. The downsizing of the connector imposed increasingly high standards for manufacturing tolerances, both for the connector housing portions and for the wire terminals. For example, by increasing the number of wires and often at the same time requiring smaller connectors, the spacing between the wires within the connector of necessity became smaller. As a result, the isolating walls between adjacent wire terminals had to be made thinner, but more importantly, in order to maintain the spacing between such isolating walls and the flexible fingers required by the molds used to make the connectors, the fingers had to be made smaller. The small connector dimensions created serious manufacturing problems, since the connector housings typically are molded from plastic materials, and the tools and dies used to form the connector parts are extremely complex. As the sizes and tolerances became smaller, the difficulty, and expense, of making the molds and maintaining them became excessive. In addition, the need to insert locking wedges into these smaller connectors in order to secure the locking fingers, and thus hold the assembled wire terminals in place without damaging the fingers made automated assembly of the harnesses very complex, and thus unsatisfactory. Yet the demand for smaller connectors with larger numbers of terminals continued, and the demand is still increasing for reductions in connector size, as well as reductions in the cost of manufacturing connector housings and wiring harnesses.
The wire terminals utilized on the individual wires used in such harnesses typically have been shaped from sheet metal through a series of precision forming steps which shaped the terminal to form either a pin (male) or a receptacle (female), these terminals being shaped to fit into corresponding connector housing lug and socket portions, respectively, for retention therein by the locking fingers and wedges described above. However, as the connectors have become miniaturized, it has been necessary to also miniaturize the wire terminals, and serious problems have been encountered in meeting the miniaturization requirements. It has been found, for example, that as the pins and receptacles are made smaller, it becomes extremely difficult to maintain proper tolerances that will insure reliable electrical contact when the connectors are mated with each other or with electrical components, or to maintain assembly forces within desired ranges. Thus, if the pin portion is too large for the receptacle portion, assembly becomes very difficult; on the other hand, if the pin is too small, then electrical contact is not reliably made. Furthermore, the precision forming steps required to make such terminals caused metal stress and fatigue which often resulted in broken terminals and resultant failure of electrical connections and produced a seam on the mating surfaces which increased assembly forces and reduced electrical contact, the precision forming of the terminals also resulted in significant scrap metal loss and rounded corners which prevented positive locking action. Further, the size and shape of such terminals required excessive motion of the locking fingers in the connectors, requiring additional space and preventing downsizing.
Thus, there has been a demand for reductions in the size of electrical connectors and/or an increase in the number of wires carried by such connectors. Further, there is a need for such connectors which can be accurately and reliably assembled, either manually or through the use of automatic machinery. When automatic machinery is used, it is desirable to avoid the necessity of inserting locking wedges, since this adds another complex step to the assembly process; however, when the harnesses are manually assembled, the use of a wedge may be desirable to insure complete insertion of all of the terminals. Thus, there is a need for a small, compact harness connector which provides positive locking for terminals when the harness is assembled by machine, so that locking wedges are not required to hold the terminals in place during use of the connector, yet which has provision for a locking wedge to insure complete insertion of the terminals when the harness is manually assembled.